Telephone transmission-circuits.



H. G. EGERTON.

TELEPHONE TRANSMISSION CIRCUITS.

APPLICATION FILED JULY 1a, 1912.

1,089,825. Patented Mar. 10, 1914.

W/lnesses: I (Q /nve/7/0r-" m Mk 3 3 Henry C. [yer/0n.

gm y (8M XVI}! UNITED STATES PATENT OFFICE.

HENRY C. EGERTON,-OF PASSAIC, NEW JERSEY, ASS IGNOR TO WESTERN ELECTRIC COMPANY, OF NEW YORK, N. Y.,.A CORPORATION OF ILLINOIS.

TELEPHONE TRANSMISSION-CIRCUITS Specification of Letters Patent.

"Patented Mar. 10,1914.

Application filed July is; 1912. Serial No. 710,108.

To all whom it may concern:

Be it known that I, HEN-RY C. Eonn'ron,

a citizen of the United States, residing at Pa ssaic, in the county of Passaic and Stateof New Jersey, have invented a certain new and useful. Improvement in Telephone Trans missioiiCircuits, of which the following isa full, clear, concise, and exact descr ption.

= This invention relates to telephone trans,

mission systems forloud speaking'appara us and more particularly to a systemin which two independent transmission circuits terr minatin at a singlestation each have conis connected for communication over one of the circuit.s,.connections will be made which will reduce the volume of sound produced by the other in case conversation is made'at the-opposite end of the line with which it is' connected.

Another object of this invention is to provide a signaling and busy indicating means for use in connection Vliill the ClIGU1tS. This feature consists in the provision of a signal at each of the stations adapted whenoperatcd to put a tone upon the line which will be audible at bothends of the lineand the volume of which indicates the condition of the apparatus at the called station.

-Other features of this invention will be more particularly described hereinafter and pointed outin the appended claims.

The due-wing illustrating this invention is a diagram of the circuits and apparatus.

'In the drawing, A and B designate waystations and O, D and E telephone circuitsterminating at said way-stations, the circuit D connecting said stations together while i the circuits C- and E extend in'opposite-"di- 'rections from the stations-A andB to other stations not shown.- Connected in bridge of the circuit D at the stati ins A and B respectively are two receiving telephones 5 and 6 of the loud speaking type.

7 and 8 designate receiving telephones connected in the circuits 0 and E respec-' tively at terminal stations A and B.

Located at the stations A and B are switch ,keys 10, 11, 12 and 13 of the double-throw type each being a two-positioned key,- one position, that shown as the lower, preferably being a lock-ingposition and the other,

that shown as the upper, being a iion l'ocle' ing position. Located at each of the stations is a telephone set 15 comprisi' 'a transmitter 16, a local battery 17 an in" 110- tion coil 18 the primary of which is in series with the local battery and thetransmitter and secondary of which is adapted to bridged across the line wires of either Keircuit C or D as will be hereinafter more hilly provided for kilos-- explained. A key 19 is 'ing the transmitter circuit and has also-a contact in the secondary circuit. Also located at each of the stations is a vibrating signaling device 22 having a local circuit controlled by either of the switch keys locatetl at that station and being provided with an inductive winding 23 which, when either of the keys'located at the corresponding station is operated into its locking position, is connected with the line wires corre sponding to that particular key. A spring ack 25 located at-each of the sta'tions is connected with line wires 26 and 27 leading through a local telephone set 28 having'a;

magneto 29 adapted when operated to oper ate a signal 30 at the way-station. A plug -31 adapted for insertion into the jack 25 connected with a telephone receiver 32 and with the telephone transmission apparatus hereinbefore described through contacts on one ofv the switchkeys located at-that station. While only one spring jack 25 is shown at each station it-will be readily understcod that any number within reasonable limits may be provided to 'enable various parties to talk with the operator, at the various stations.

Resistance devices 38 and 39 located at each of the stations are so connected with the contacts of the two keys at their corre-" sponding station that the operation of one of the keys after connecting the transmission apparatus with its corresponding circuit connects oneyof the resistances in bridge of the other circuit and in shunt of the. receiver connected with that circuit at the stat-i011 at" which the key is, operated. This feature may be more clearly understood b 'tracing the circuits established in this operation, and

which are as follows: Assume that the open or station" A desiresto communicate 'at bfoue'ziialdeto The ell having been madeythe operator atA will "operate his key into its non-locking position to actuate the corresponding springs and will iilso; depress his :key'19 to close his limosling ion ci guit. "Assumin that he has comlete ditliis'ofierationfit w: 1 be" noted that he as closedhis'local transmitter circuit and 'ithe' secondary circuit and thus completed the ';tal king circuit over the lines of C which iimay betraced as follows; from line wire through contact 4l-of the key 10, condoctor 42-, secondary of the induction coil .-18,*contact 43'of the key 19, conductor 4 contact 45 of the key 1 0 conductoi to the other lineconductor 4 of the circuit C.

G. Simultaneously withthe completion of t-his circuit, however, other contactson the key 10.'are closed which connect the 25" resistance 39 in bridge of the wires of the 'circuit D, this circuit being, traced as fol- 1 v lows: from conductor of the circuit 'D, conductor 51, resistance 39, contact 52 of the -key 10, conductor 53 and'conductor 54 to thevother line conductor'55 of the circuit D. The resistances 38- and 39 are low as compared with'the resistances of the receiving telephones'5, 6, 7 and 8'and consequently atford a considerable shunt-to these instruments, thus enabling the operator;- when talking over one of the circuits to effectively reduce the volume of sound which would resuit from the operation of the adjacent re-.

' -.ceiver in the other circuit in case the oper- 40 Yator-at the opposite end to that particular line should-s gnal or talk.- ,This reduction, -however,' i s :n ot so great but that'the operator talking-over-one line circuit will be aware of a s'ignal or communication sentover the other line circuit terminating in his ofiice; Similarly, the operation of the key 11. into its non-locking position will connect-the operator at A or communication with the operator at B, shunt the receiver '2 with the resistance 38, and 'operatively connect the telephone set 15 with the circuit D. Y

\ ;Referring-now to the method by means of -which one operator signals another, this may bebest-understoodby f ollowing the circuits involved" in the process; Assuming that the operator at station A desires to signal;i-the operatorat station, B he does so by .--ppera t i n key 11 into its lockin position to springs. he z'etuationof this key into this position closes a'local energizing circuit for Y the signal 22 which may betraced from one side of the battery 60, conductor til, vibrat ing contact 62 of the signal, theenergizing th the operator'at t-heidistant end f cir-L ,Qeither on a call made bythe operator ill hiscompletes the circuit for the outgoing g-voitae currents from the station A over the sound in the receivers a Open an close the correspon ing contact winding of the signal 22, conductor 63, conductor 64, contact 65 of the key 11, conductor '67 and conductor 68 to the other side-of the battery 60. As this contact vibrates, it inductors 54 and 70, contact 71 of the switch 11, conductor 72through the inductive windihg 230i the-relay, conductor 73, contact 74 of gthe key 10, conductor 75, conductor 76,

contact 78 of the key 11, conductor 79, conductor 50 of the circuit D, and over thi's'liue wire through thereceiver 6 to the conductor a 55. This produces a tonewhich will be audible in the .receiver 6.connected at the other end of the circuit Dandalso' will be heard in the receiver 5 connected with the I end of the circuit-,1) froin vwhich thesignal emanates. This tone'will notity the operator at station B that communication with him is desired by the operator at station A. If the operator at Station B, howeven-is busy with a communication over the circuit E be will, of course, have operated his key 13 into its non-locking position to bridge the resistance 38 across the line wircs of the-circuit D in a manner similar to that traced at the station A. \Vith this resistance in bridge of the wires of the circuit D the volume of the and 6 resulting from the operation of the signal 22 will be greatly reduced, thus indicatlng'to the callingoperator that the operator at the'distant fiend of the line is busy. The key ll being adapted to lock in its operated position, the

operator at station A by leaving this key in its locked position will be able to determine immediately the completion of the communication at the other station by reason of the fact that. as soon as this conversationis completed, the key 13 will be released, thus opening a circuit of the resistance '38 which will be immediately noticeable by the increased tone upon the line. Obviously a scheme of this sort provides a convenient and efficient means for obtaining the best results in the system to which it is 'applied, enabling an operate" to carry on a communication with i any 0th operator without disturbance from an adjacent line and still be sufliciently in touch with said adjacentline that any communication of importance can be given immediate attention. This feature is particularly important in railway work where the system may be used for receiving and giving orders for the movement of hair What I claim is: l 1. In a telephone transmission sy. .1, two independent telephone circuits terminating at one station, receiving telephones connected one each of said circuits, transmission apparatus at said station, means for operatively connecting said transmission apparaed in each of said circuits, transmission apparatus at said station, volume reducing means for each of said receiving telephones,

and means .tor operatively connecting said telephone transmission apparatus with one of said circuits and sin'uiltaneously rendering effective the volume reducing means of the receiving telephone in the other of said circuits.

3. In a telephone transmission system, two independent telephone circuits terminating at one station, receiving telephones connect-- ed one in each of said circuits and located at said station, transmission apparatus, switch ing means for operatively connecting said transmissionapparatus with either of said telephone circuits and a normally disabled resistance device for each line circuit connected in shunt of the receiving telephone 0 its'line when the transmission apparatus is operatively connected with the other of said lines.

4. In a telephone transmission system, two independent telephone circuits teri'ninating at one station, receiving telephones connect ed one in each of said circuits, normally disabled resistances for said circuits, transmis sion apparatus, switching means for operatively connecting said transmission apparatus with one of said telephone circuits and simultaneously connecting one of said resistances in shunt. of the receiving telephone in the other of said circuits.

5. In a telephone transmission system the combination of two telephones in audible, interfering proximity, a separate main circuit for each, transmitting apparatus, a switching dev ce and means whereby'said switching device when operated places the transmission apparatus in circuit with one receiver and renders the articulation of the other receiver practically inaudible.

6. In a. telephone transnn sion system, two independent telephone circuits terminating at one end in a common. station and at their opposite ends in separate stations, receiving telephones one in each circuit at said common station, and in each circuit at the separate stations, means ici: reducing the volume of sound in any of said receiving telephones of any of id lines and means the opposite end of the same line for determining the .ondition of said receiving telephone.

7. In a telephone tran ion system two independent telephone terminating at one end in a common station and at their opposite ends in separate stations, recei'iing telephones one in circuit at each of said stations, transm" ion apparr s at each of said stations, m ans for cperzcivci connecting said trans-mi on apparatus with the line tcrminatin t the ccn'nncn station and shunting the receiving telephone of the other line, and means for impressing a, tane upon the line at any station the volun c of said tone heinf reiined by the ccnd :ion of the rot .tie end of the line upon JilfslCl 'ipri i,

8. In a telephone transmis on system two independent telephone circnlts teri'ninating at one end in a common station and at their opposite ends in separate stations, receiving telephones one in each circuit at each of said stations, telephone transmission apparatus at each of said stations, tone inducing at each of said. stations a two position switch and connections whereby said switch when in one position connects said transmi sion apparatus with a line and in its otl position ()Pfiftitl h; connects said tone 1n- (lacing means W: i the same line- In witness whereof, i. hereunto subscribe (if July .1 1 I), lilli'l.

' ,hlalii litfflN.

I'Vitnesses Momma l CONATE, been .il'nicnn. 

